1. Field of the Invention
This invention relates to a method of etching a surface of a substrate comprising LiTaO.sub.3 and chemically similar materials and more particularly, to a method of etching LiTaO.sub.3 with a mixture comprising hydrofluoric acid and sulfuric acid.
2. Description of the Prior Art
Recently, lithium tantalate (LiTaO.sub.3) has become of great interest in the electrical device industry. An inherent problem in the use of LiTaO.sub.3 has been the etching and polishing of this material. Lithium tantalate (LiTaO.sub.3) can be etched with an aqueous mixture consisting of HNO.sub.3 and HF. However, the etching can only be carried out at a reasonable rate at the boiling temperature of the mixture. With respect to the polishing of LiTaO.sub.3, the HNO.sub.3 -HF mixture does not polish a surface of LiTAO.sub.3 so that optical inspection thereof for surface and interior defects is possible. An etchant which both etches the LiTaO.sub.3 and polishes a surface thereof at a reasonable rate at a moderate temperature is therefore desirable and a method of employing such an etchant is an object of this invention.